Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description must disclose behavior. It mentions the payback arithmetic and factual scope (e.g., 'No federal purchase premium'), but it does not explicitly describe how the tool processes parameters or what outputs to expect. The temporal 'Stand 08/2026' and the apply-before-buying rule add useful context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a concise two-sentence structure with a German and English version. It front-loads the topic and packs measurable value without excessive fluff. The inclusion of a data freshness date is useful.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the schema and lack of output schema, the description is reasonably complete for an informational tool. It conveys the main topics and the key rule (apply-before-buying), but it does not explicitly state the output format or all edge-case behaviors (e.g., invalid bundesland, missing parameters).

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% for all four parameters, so the baseline is 3. The description adds some context by referencing state programmes (bundesland) and payback arithmetic (zuschuss_eur/ersparnis_eur_jahr), but it does not go beyond what the schema already explains.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description explicitly states the tool covers German subsidies for balcony solar and storage, including state programmes, the storage bonus, the apply-before-buying rule, and payback arithmetic. This is a specific resource and clearly distinguishes it from siblings like btu_empfehlung or klimaanlage_stromkosten.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage by listing the covered topics, but it lacks explicit guidance on when to use this tool versus alternatives or when not to use it. No sibling tools are mentioned, and there are no exclusions or prerequisite conditions given.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.